Replace hidden flag with post state.

Store post state as text so Go owns the allowed values and future states such as locked remain representable without a database enum migration.

internal/store/post.go

@@ -21,6 +21,14 @@ var (
 	ErrPostNotVotable = errors.New("post not votable")
 )
 
+type PostState string
+
+const (
+	PostStateVisible PostState = "visible"
+	PostStateHidden  PostState = "hidden"
+	PostStateLocked  PostState = "locked"
+)
+
 // Post is either a root question (ParentID nil) or a reply to another post.
 type Post struct {
 	ID         string
@@ -32,7 +40,7 @@ type Post struct {
 	Body       string
 	City       string
 	PostDate   string
-	Hidden     bool
+	PostState  PostState
 	CreatedAt  string
 	UpdatedAt  string
 	Score      int
@@ -63,7 +71,7 @@ func (p *Post) Create(ctx context.Context) error {
 		Body:      p.Body,
 		City:      p.City,
 		PostDate:  p.PostDate,
-		Hidden:    boolInt32(p.Hidden),
+		PostState: string(p.PostState),
 		CreatedAt: p.CreatedAt,
 		UpdatedAt: p.UpdatedAt,
 	})
@@ -101,6 +109,14 @@ func preparePost(p *Post) error {
 	p.Body = strings.TrimSpace(p.Body)
 	p.City = strings.TrimSpace(p.City)
 	p.PostDate = strings.TrimSpace(p.PostDate)
+	if p.PostState == "" {
+		p.PostState = PostStateVisible
+	}
+	switch p.PostState {
+	case PostStateVisible, PostStateHidden, PostStateLocked:
+	default:
+		return fmt.Errorf("%w: invalid post state", ErrInvalidPost)
+	}
 	if p.AuthorID == "" {
 		return fmt.Errorf("%w: author is required", ErrInvalidPost)
 	}
@@ -120,7 +136,7 @@ func preparePost(p *Post) error {
 			return fmt.Errorf("%w: parent is required", ErrInvalidPost)
 		}
 		p.ParentID = &parentID
-		if p.Title != "" || p.City != "" || p.PostDate != "" || p.Hidden {
+		if p.Title != "" || p.City != "" || p.PostDate != "" || p.PostState != PostStateVisible {
 			return fmt.Errorf("%w: reply contains root-only fields", ErrInvalidPost)
 		}
 	}
@@ -152,13 +168,6 @@ func parentIDFromNull(parentID sql.NullString) *string {
 	return &id
 }
 
-func boolInt32(value bool) int32 {
-	if value {
-		return 1
-	}
-	return 0
-}
-
 func mapPostCreateError(err error) error {
 	if err == nil {
 		return nil
@@ -178,7 +187,7 @@ func postFromValues(
 	id string,
 	parentID sql.NullString,
 	authorID, authorName, authorRole, title, body, city, postDate string,
-	hidden int32,
+	postState string,
 	createdAt, updatedAt string,
 ) Post {
 	return Post{
@@ -191,7 +200,7 @@ func postFromValues(
 		Body:       body,
 		City:       city,
 		PostDate:   postDate,
-		Hidden:     hidden != 0,
+		PostState:  PostState(postState),
 		CreatedAt:  createdAt,
 		UpdatedAt:  updatedAt,
 		db:         db,
@@ -215,7 +224,7 @@ func GetPost(ctx context.Context, db *sql.DB, id string) (*Post, error) {
 		r.Body,
 		r.City,
 		r.PostDate,
-		r.Hidden,
+		r.PostState,
 		r.CreatedAt,
 		r.UpdatedAt,
 	)
@@ -241,7 +250,7 @@ func GetPostThread(ctx context.Context, db *sql.DB, rootID string) (*Post, error
 			r.Body,
 			r.City,
 			r.PostDate,
-			r.Hidden,
+			r.PostState,
 			r.CreatedAt,
 			r.UpdatedAt,
 		))
@@ -292,9 +301,10 @@ func buildPostTree(posts []Post, rootID string) (*Post, error) {
 // ListRootPosts returns visible root posts for a post date.
 func ListRootPosts(ctx context.Context, db *sql.DB, postDate, viewerID string) ([]Post, error) {
 	rows, err := sqlc.New(db).ListRootPosts(ctx, sqlc.ListRootPostsParams{
-		ViewerID: viewerID,
-		RowLimit: HuntListLimit,
-		PostDate: postDate,
+		ViewerID:    viewerID,
+		RowLimit:    HuntListLimit,
+		PostDate:    postDate,
+		HiddenState: string(PostStateHidden),
 	})
 	if err != nil {
 		return nil, err
@@ -312,7 +322,7 @@ func ListRootPosts(ctx context.Context, db *sql.DB, postDate, viewerID string) (
 			r.Body,
 			r.City,
 			r.PostDate,
-			r.Hidden,
+			r.PostState,
 			r.CreatedAt,
 			r.UpdatedAt,
 		)
@@ -331,7 +341,10 @@ func SetPostVote(ctx context.Context, db *sql.DB, userID, postID string, value i
 	}
 	q := sqlc.New(db)
 	if value == 0 {
-		visible, err := q.PostIsVisibleRoot(ctx, postID)
+		visible, err := q.PostIsVisibleRoot(ctx, sqlc.PostIsVisibleRootParams{
+			ID:          postID,
+			HiddenState: string(PostStateHidden),
+		})
 		if err != nil {
 			return err
 		}
@@ -344,9 +357,10 @@ func SetPostVote(ctx context.Context, db *sql.DB, userID, postID string, value i
 		})
 	}
 	n, err := q.UpsertPostVoteOnVisibleRoot(ctx, sqlc.UpsertPostVoteOnVisibleRootParams{
-		UserID: userID,
-		PostID: postID,
-		Value:  int32(value),
+		UserID:      userID,
+		PostID:      postID,
+		Value:       int32(value),
+		HiddenState: string(PostStateHidden),
 	})
 	if err != nil {
 		return err